1. Field of Invention
The invention relates to a measuring instrument, more particularly to a level vial which is used to measure whether a surface is level.
2. Discussion of the Related Art
A level vial is widely used measuring instrument for measuring the level of a surface. In construction works or installation of machines or household furniture such as installing a window in a house, the first thing an engineer will be cautious of is the alignment of the window related to the wall and the ground level. If the window is mounted improperly, it will most likely not be aligned with a true vertical line, and will therefore not look right. In the same manner, if a punch machine is mounted inclinedly with respect to a true horizontal line, the operator may encounter difficulty in operating it properly. A level vial is therefore used for measuring whether the surface on which a window or a machine is to be mounted is truly horizontal.
But there are things that occasionally need to be mounted on a certain inclination with respect to a true horizontal or vertical line. The absolute inclination with respect to a true horizontal line can also be measured with a level vial.
FIGS. 1(A) and (B) show two kinds of highly sophisticated level vials. FIG. 1(A) shows a theodolite of prior art which is used to measure the horizontal and vertical level of a surface. FIG. 1(B) is an automatic level vial of prior art, containing a liquid vial which cannot be witnessed from outside. Their sophistication though, makes them relatively easy to damage.
For general use, a flexible transparent plastic pipe (1) containing water (2) as shown in FIG. 2 is generally substituted for a level vial. But this kind of vial has the following defects.
(1) Since there is no closing means on the ends of the pipe, two people are required to use this device, one to hold each end of the pipe until water in the pipe stablizes.
(2) Water may spill out of the pipe when the pipe is moved to a working site.
(3) In places where there is no water to fill the pipe, the instrument is not workable.
(4) Dirt or unnecessary things be get into the pipe, which could spoil the water inside of the same.
(5) Water by itself is a transparent matter, the plastic pipe is also transparent, therefore it is sometimes hard to distinguish the water level in the pipe.
(6) If the user accidentally raises one end of the pipe, the water may run out of the pipe, which is not very convenient for the user.